Food and chemical allergy and intolerance are difficult and poorly understood problems in clinical medicine. It has been estimated that up to 10% of the United States population has experienced symptoms attributable to hypersensitivity to food and chemicals and/or aggravation of their symptoms by elements in their diets. The diagnosis of food and chemical allergies remains an unsettled issue and the various tests heretofore employed are subject to numerous problems.
In addition to the RAST test, the test which has received the most attention for determining food and chemical allergies is known as the cytotoxic food test. This test is based on the fact that structural changes which are observable under the microscope are undergone by the living polymorphonuclear cells of the sensitive patient when exposed in vitro to the incriminated fool allergen. Such changes include cessation of motility, loss of pseudopods, vacuolation, and, in the most severe cases, disruption of the leukocytic cell membrane with the formation of so called "ghost cells". The cytotoxic food test was introduced into clinical use by Black in 1956. There have been several reports, before and since that time, concerning the morphologic alterations in segmented leukocytes induced by exposure to allergies. One notable exception to such reports was the experience of Franklin and Lowell who were unable to observe lysis of leukocytes after their exposure to ragweed allergens in patients with ragweed hypersensitivity.
In the cytotoxic food test, the polymorphonuclear cells are examined without any histochemical stains. The structural changes are often subtle and the evaluation of those changes is extremely subjective. As a result, wide variations in the results obtained by different observers has been a major source of dissatisfaction with this diagnostic technique.
A parallel diagnostic approach was investigated by monitoring the changes in the polymorphonuclear cell count in the circulating blood in patients with food allergies after they were challenged with the incriminated foods. A marked fall in the leukocyte count under these circumstances was considered a positive reaction. This diagnostic test is unsatisfactory because it is frequently negative in patients with known food allergies.
It is the object of this invention to provide a reliable in vitro test for determining food or chemical allergy or intolerance and thereby overcome the disadvantages of the prior art approaches. This and other objects of the invention will become apparent to those skilled in the art from the following detailed description of the invention.